Methods :
Quarter-DMEK grafts were obtained from 10 corneas with intact and viable endothelial cells but ineligible for transplantation. 10 Quarter-DMEK grafts were “sandwiched” between 2 glass slides and cultured over 1 week in a humidified atmosphere at 37°C and 5% CO2. Cell movement was assessed by light microscopy at standardized time intervals. In addition, immunohistochemistry analysis were performed to assess the detailed structural organization of endothelial cells in the corneal center and far periphery.

Results :
Endothelial cell outgrowth occurred from the radial cut graft edges, but not from the far peripheral area. Cell migration followed three different migration patterns: 1. individual cell migration, 2. uncoordinated cell migration of cell clusters, and 3. collective migration in which endothelial cells move as a sheet. Immunostaining showed presence of endothelial cells up to the far periphery but with different expression patters of phenotypical markers ZO-1, Na+/K+ -ATPase, and vimentin than for central endothelial cells.

Conclusions :
In-vitro endothelial cell migration from Quarter-DMEK grafts occurs along the radial cut edges with a decrease in migration activity towards the corneal far periphery. No migration occurred along the outer peripheral corneal edge which may be caused by a different anatomical matrix in the far periphery. Hence, the endothelial cells from the far periphery may not contribute to corneal clearance of the adjacent bare area after Quarter-DMEK surgery, but these cells may constitute a valuable cellular reserve on the graft.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.